TY - GEN A1 - Elsenbeer, Helmut A1 - West, Adam A1 - Bonell, Mike T1 - Hydrologic pathways and stormflow hydrochemistry at South Creek, northeast Queensland N2 - Earlier investigations at South Creek in northeastern Queensland established the importance of overland flow as a hydrologic pathway in this tropical rainforest environment. Since this pathway is ‘fast’, transmitting presumably ‘new’ water, its importance should be reflected in the stormflow chemistry of South Creek: the greater the volumentric contribution to the stormflow hydrograph, the more similarity between the chemical composition of streamwater and of overland flow is to be expected. Water samples were taken during two storm events in an ephemeral gully (gully A), an intermittent gully (gully B) and at the South Creek catchment outlet; additional spot checks were made in several poorly defined rills. The chemical composition of ‘old’ water was determined from 45 baseflow samples collected throughout February. The two events differed considerably in their magnitudes, intensities and antecedent moisture conditions. In both events, the stormflow chemistry in South Creek was characterized by a sharp decrease in Ca, Mg, Na, Si, Cl, EC, ANC, alkalinity and total inorganic carbon. pH remained nearly constant with discharge, whereas K increased sharply, as did sulfate in an ill-defined manner. In event 1, this South Creek stormflow pattern was closely matched by the pattern in gully A, implying a dominant contribution of ‘new’ water. This match was confirmed by the spot samples from rills. Gully B behaved like South Creek itself, but with a dampened ‘new’ water signal, indicating less overland flow generation in its subcatchment. In event 2, which occurred five days later, the initial ‘new’ water signal in gully A was rapidly overwhelmed by a different signal which is attributed to rapid drainage from a perched water table. This study shows that stormflow in this rainforest catchment consists predominantly of ‘new’ water which reaches the stream channel via ‘fast’ pathways. Where the ephemeral gullies delivering overland flow are incised deeply enough to intersect a perched water table, a delayed, ‘old’ water-like signal may be transmitted. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 046 Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-16904 ER - TY - JOUR A1 - Vorpahl, Peter A1 - Elsenbeer, Helmut A1 - Märker, Michael A1 - Schröder-Esselbach, Boris T1 - How can statistical models help to determine driving factors of landslides? JF - Ecological modelling : international journal on ecological modelling and engineering and systems ecolog N2 - Landslides are a hazard for humans and artificial structures. From an ecological point of view, they represent an important ecosystem disturbance, especially in tropical montane forests. Here, shallow translational landslides are a frequent natural phenomenon and one local determinant of high levels of biodiversity. In this paper, we apply weighted ensembles of advanced phenomenological models from statistics and machine learning to analyze the driving factors of natural landslides in a tropical montane forest in South Ecuador. We exclusively interpret terrain attributes, derived from a digital elevation model, as proxies to several driving factors of landslides and use them as predictors in our models which are trained on a set of five historical landslide inventories. We check the model generality by transferring them in time and use three common performance criteria (i.e. AUC, explained deviance and slope of model calibration curve) to, on the one hand, compare several state-of-the-art model approaches and on the other hand, to create weighted model ensembles. Our results suggest that it is important to consider more than one single performance criterion. Approaching our main question, we compare responses of weighted model ensembles that were trained on distinct functional units of landslides (i.e. initiation, transport and deposition zones). This way, we are able to show that it is quite possible to deduce driving factors of landslides, if the consistency between the training data and the processes is maintained. Opening the 'black box' of statistical models by interpreting univariate model response curves and relative importance of single predictors regarding their plausibility, we provide a means to verify this consistency. With the exception of classification tree analysis, all techniques performed comparably well in our case study while being outperformed by weighted model ensembles. Univariate response curves of models trained on distinct functional units of landslides exposed different shapes following our expectations. Our results indicate the occurrence of landslides to be mainly controlled by factors related to the general position along a slope (i.e. ridge, open slope or valley) while landslide initiation seems to be favored by small scale convexities on otherwise plain open slopes. KW - Landslides KW - Tropical montane forests KW - Statistical modeling KW - Model comparison KW - Artificial neuronal network KW - Classification trees KW - Random forests KW - Boosted regression trees KW - Generalized linear models KW - Multivariate adaptive regression splines KW - Maximum entropy method KW - Weighted model ensembles Y1 - 2012 U6 - https://doi.org/10.1016/j.ecolmodel.2011.12.007 SN - 0304-3800 SN - 1872-7026 VL - 239 IS - 7 SP - 27 EP - 39 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Messmer, Tobias A1 - Elsenbeer, Helmut A1 - Wilcke, Wolfgang T1 - High exchangeable calcium concentrations in soils on Barro Colorado Island, Panama JF - Geoderma : an international journal of soil science N2 - The soils on four lithologies (basaltic conglomerates, Bohio; Andesite; volcanoclastic sediments with basaltic agglomerates, Caimito volcanic; foraminiferal limestone, Caimito marine) on Barro Colorado Island (BCI have high exchangeable Ca concentrations and cation-exchange capacities (CEC) compared to other tropical soils on similar parent material. In the 0-10 cm layer of 24 mineral soils, pH values ranged from 5.7 (Caimito volcanic and Andesite) to 6.5 (Caimito marine), concentrations of exchangeable Ca from 134 mmol(c) kg(-1) (Caimito volcanic) to 585 mmolc kg-1 (Caimito marine), and cation exchange capacities from 317 mmol(c) kg(-1) (Caimito volcanic) to 933 mmol(c) kg(-1) (Caimito marine). X-ray diffractometry of the fraction <2 mu m revealed that smectites dominated the clay mineral assemblage in soil except on Caimito volcanic, where kaolinite was the dominant clay mineral. Exchangeable Ca concentrations decreased with increasing soil depth except on Caimito marine. The weathering indices Chemical Index of Alteration (CIA), Plagioclase Index of Alteration (PIA) and Weathering Index of Parker (WIP) determined for five soils on all geological formations, suggested that in contrast to expectation the topsoil (0-10 cm) appeared to be the least and the subsoil (50-70 cm) and saprolite (isomorphically weathered rock in the soil matrix) the most weathered. Additionally, the weathering indices indicated depletion of base cations and enrichment of Al-(hydr)oxides throughout the soil profile. Tree species did not have an effect on soil properties. Impeded leaching and the related occurrence of overland flow seem to be important in determining clay mineralogy. Our results suggest that (i) edaphic conditions favor the formation of smectites on most lithologies resulting in high CEC and thus high retention capacity for Ca and (ii) that there is an external source such as dust or sea spray deposition supplying Ca to the soils. KW - Panama KW - Cation-exchange capacity KW - Exchangeable Ca KW - Clay mineralogy KW - Weathering indices Y1 - 2014 U6 - https://doi.org/10.1016/j.geoderma.2013.10.021 SN - 0016-7061 SN - 1872-6259 VL - 217 SP - 212 EP - 224 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Zimmermann, Alexander A1 - Francke, Till A1 - Elsenbeer, Helmut T1 - Forests and erosion: Insights from a study of suspended-sediment dynamics in an overland flow-prone rainforest catchment JF - Journal of hydrology N2 - Forests seem to represent low-erosion systems, according to most, but not all, studies of suspended-sediment yield. We surmised that this impression reflects an accidental bias in the selection of monitoring sites towards those with prevailing vertical hydrological flowpaths, rather than a tight causal link between vegetation cover and erosion alone. To evaluate this conjecture, we monitored, over a 2-year period, a 3.3 ha old-growth rainforest catchment prone to frequent and widespread overland flow. We sampled stream flow at two and overland flow at three sites in a nested arrangement on a within-event basis, and monitored the spatial and temporal frequency of overland flow. Suspended-sediment concentrations were modeled with Random Forest and Quantile Regression Forest to be able to estimate the annual yields for the 2 years, which amounted to 1 t ha(-1) and 2 t ha(-1) in a year with below-average and with average precipitation, respectively. These estimates place our monitoring site near the high end of reported suspended-sediment yields and lend credence to the notion that low yields reflect primarily the dominance of vertical flowpaths and not necessarily and exclusively the kind of vegetative cover. Undisturbed forest and surface erosion are certainly no contradiction in terms even in the absence of mass movements. KW - Rainforest KW - Overland flow KW - Erosion KW - Suspended-sediment yield KW - Quantile Regression Forest model KW - Panama Canal watershed Y1 - 2012 U6 - https://doi.org/10.1016/j.jhydrol.2012.01.039 SN - 0022-1694 VL - 428 IS - 7 SP - 170 EP - 181 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Haßler, Sibylle Kathrin A1 - Lark, Richard M. A1 - Milne, A. E. A1 - Elsenbeer, Helmut T1 - Exploring the variation in soil saturated hydraulic conductivity under a tropical rainforest using the wavelet transform JF - European journal of soil science N2 - Saturated hydraulic conductivity (Ks) of the soil is a key variable in the water cycle. For the humid tropics, information about spatial scales of Ks and their relation to soil types deduced from soil map units is of interest, as soil maps are often the only available data source for modelling. We examined the influence of soil map units on the mean and variation in Ks along a transect in a tropical rainforest using undisturbed soil cores at 06 and 612 cm depth. The Ks means were estimated with a linear mixed model fitted by residual maximum likelihood (REML), and the spatial variation in Ks was investigated with the maximum overlap discrete wavelet packet transform (MODWPT). The mean values of Ks did not differ between soil map units. The best wavelet packet basis for Ks at 06 cm showed stationarity at high frequencies, suggesting uniform small-scale influences such as bioturbation. There were substantial contributions to wavelet packet variance over the range of spatial frequencies and a pronounced low frequency peak corresponding approximately to the scale of soil map units. However, in the relevant frequency intervals no significant changes in wavelet packet variance were detected. We conclude that near-surface Ks is not dominated by static, soil-inherent properties for the examined range of soils. Several indicators from the wavelet packet analysis hint at the more dominant dynamic influence of biotic processes, which should be kept in mind when modelling soil hydraulic properties on the basis of soil maps. Y1 - 2011 U6 - https://doi.org/10.1111/j.1365-2389.2011.01400.x SN - 1351-0754 VL - 62 IS - 6 SP - 891 EP - 901 PB - Wiley-Blackwell CY - Malden ER - TY - JOUR A1 - Germer, Sonja A1 - Zimmermann, Alexander A1 - Neill, Christopher A1 - Krusche, Alex V. A1 - Elsenbeer, Helmut T1 - Disproportionate single-species contribution to canopy-soil nutrient flux in an Amazonian rainforest JF - Forest ecology and management N2 - Rainfall, throughfall and stemflow were monitored on an event basis in an undisturbed open tropical rainforest with a large number of palm trees located in the southwestern Amazon basin of Brazil. Stemflow samples were collected from 24 trees with a diameter at breast height (DBH) > 5 cm, as well as eight young and four full-grown babassu palms (Attalea speciosa Mart.) for 5 weeks during the peak of the wet season. We calculated rainfall, throughfall and stemflow concentrations and fluxes of Na+, K+, Ca2+, Mg2+,, Cl-, SO42-, NO3- and H+ and stemflow volume-weighted mean concentrations and fluxes for three size classes of broadleaf trees and three size classes of palms. The concentrations of most solutes were higher in stemflow than in rainfall and increased with increasing tree and palm size. Concentration enrichments from rainfall to stemflow and throughfall were particularly high (81-fold) for NO3-. Stemflow fluxes of NO3- and H+ exceeded throughfall fluxes but stemflow fluxes of other solutes were less than throughfall fluxes. Stemflow solute fluxes to the forest soil were dominated by fluxes on babassu palms, which represented only 4% of total stem number and 10% of total basal area. For NO3-, stemflow contributed 51% of the total mass of nitrogen delivered to the forest floor (stemflow + throughfall) and represented more than a 2000-fold increase in NO3- flux compared what would have been delivered by rainfall alone on the equivalent area. Because these highly localized fluxes of both water and NO3- persist in time and space, they have the potential to affect patterns of soil moisture, microbial populations and other features of soil biogeochemistry conducive to the creation of hotspots for nitrogen leaching and denitrification, which could amount to an important fraction of total ecosystem fluxes. Because these hotspots occur over very small areas, they have likely gone undetected in previous studies and need to be considered as an important feature of the biogeochemistry of palm-rich tropical forest. KW - Stemflow KW - Throughfall KW - DBH KW - Open tropical rain forest KW - Babassu palm (Attalea speciosa Mart. synonym: Orbignya phalerata Mart.) KW - Amazonia Y1 - 2012 U6 - https://doi.org/10.1016/j.foreco.2011.11.041 SN - 0378-1127 VL - 267 IS - 2 SP - 40 EP - 49 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Bäse, Frank A1 - Elsenbeer, Helmut A1 - Neill, Christopher A1 - Krusche, Alex V. T1 - Differences in throughfall and net precipitation between soybean and transitional tropical forest in the southern Amazon, Brazil JF - Agriculture, ecosystems & environment : an international journal for scientific research on the relationship of agriculture and food production to the biosphere N2 - The expansion of soybean cultivation into the Amazon in Brazil has potential hydrological effects at local to regional scales. To determine the impacts of soybean agriculture on hydrology, a comparison of net precipitation (throughfall, stemflow) in undisturbed tropical forest and soybean fields on the southern edge of the Amazon Basin in the state of Mato Grosso is needed. This study measured throughfall with troughs and stemflow with collar collectors during two rainy seasons. The results showed that in forest 91.6% of rainfall was collected as throughfall and 0.3% as stemflow, while in soybean fields with two-month old plants, 46.2% of rainfall was collected as throughfall and 9.0% as stemflow. Hence, interception of precipitation in soybean fields was far greater than in intact forests. Differences in throughfall, stemflow and net precipitation were found to be mainly associated with differences in plant structure and stem density in transitional forest and soybean cropland. Because rainfall interception in soybean fields is higher than previously believed and because both the area of cropland and the frequency of crop cycles (double cropping) are increasing rapidly, interception needs to be reconsidered in regional water balance models when consequences of land cover changes are analyzed in the Amazon soybean frontier region. Based on the continued expansion of soybean fields across the landscape and the finding that net precipitation is lower in soy agriculture, a reduction in water availability in the long term can be assumed. KW - Throughfall KW - Net precipitation KW - Stemflow KW - Soybean KW - Tropical forest Y1 - 2012 U6 - https://doi.org/10.1016/j.agee.2012.06.013 SN - 0167-8809 VL - 159 SP - 19 EP - 28 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Hayhoe, Shelby J. A1 - Neill, Christopher A1 - Porder, Stephen A1 - McHorney, Richard A1 - Lefebvre, Paul A1 - Coe, Michael T. A1 - Elsenbeer, Helmut A1 - Krusche, Alex V. T1 - Conversion to soy on the Amazonian agricultural frontier increases streamflow without affecting stormflow dynamics JF - Global change biology N2 - Large-scale soy agriculture in the southern Brazilian Amazon now rivals deforestation for pasture as the region's predominant form of land use change. Such landscape-level change can have substantial consequences for local and regional hydrology, but these effects remain relatively unstudied in this ecologically and economically important region. We examined how the conversion to soy agriculture influences water balances and stormflows using stream discharge (water yields) and the timing of discharge (stream hydrographs) in small (2.5-13.5 km2) forested and soy headwater watersheds in the Upper Xingu Watershed in the state of Mato Grosso, Brazil. We monitored water yield for 1 year in three forested and four soy watersheds. Mean daily water yields were approximately four times higher in soy than forested watersheds, and soy watersheds showed greater seasonal variability in discharge. The contribution of stormflows to annual streamflow in all streams was low (< 13% of annual streamflow), and the contribution of stormflow to streamflow did not differ between land uses. If the increases in water yield observed in this study are typical, landscape-scale conversion to soy substantially alters water-balance, potentially altering the regional hydrology over large areas of the southern Amazon. KW - Amazon KW - baseflow KW - hydrology KW - land use change KW - soybean cultivation KW - water yield Y1 - 2011 U6 - https://doi.org/10.1111/j.1365-2486.2011.02392.x SN - 1354-1013 VL - 17 IS - 5 SP - 1821 EP - 1833 PB - Wiley-Blackwell CY - Malden ER - TY - JOUR A1 - Zimmermann, Beate A1 - Zimmermann, Alexander A1 - Turner, Benjamin L. A1 - Francke, Till A1 - Elsenbeer, Helmut T1 - Connectivity of overland flow by drainage network expansion in a rain forest catchment JF - Water resources research N2 - Soils in various places of the Panama Canal Watershed feature a low saturated hydraulic conductivity (K-s) at shallow depth, which promotes overland-flow generation and associated flashy catchment responses. In undisturbed forests of these areas, overland flow is concentrated in flow lines that extend the channel network and provide hydrological connectivity between hillslopes and streams. To understand the dynamics of overland-flow connectivity, as well as the impact of connectivity on catchment response, we studied an undisturbed headwater catchment by monitoring overland-flow occurrence in all flow lines and discharge, suspended sediment, and total phosphorus at the catchment outlet. We find that connectivity is strongly influenced by seasonal variation in antecedent wetness and can develop even under light rainfall conditions. Connectivity increased rapidly as rainfall frequency increased, eventually leading to full connectivity and surficial drainage of entire hillslopes. Connectivity was nonlinearly related to catchment response. However, additional information on factors such as overland-flow volume would be required to constrain relationships between connectivity, stormflow, and the export of suspended sediment and phosphorus. The effort to monitor those factors would be substantial, so we advocate applying the established links between rain event characteristics, drainage network expansion by flow lines, and catchment response for predictive modeling and catchment classification in forests of the Panama Canal Watershed and in similar regions elsewhere. KW - connectivity KW - overland flow KW - stormflow KW - suspended sediment KW - phosphorus KW - drainage network expansion Y1 - 2014 U6 - https://doi.org/10.1002/2012WR012660 SN - 0043-1397 SN - 1944-7973 VL - 50 IS - 2 SP - 1457 EP - 1473 PB - American Geophysical Union CY - Washington ER - TY - GEN A1 - Elsenbeer, Helmut A1 - Lack, Andreas A1 - Cassel, Keith T1 - Chemical fingerprints of hydrological compartments and flow paths at La Cuenca, western Amazonia N2 - A forested first-order catchment in western Amazonia was monitored for 2 years to determine the chemical fingerprints of precipitation, throughfall, overland flow, pipe flow, soil water, groundwater, and streamflow. We used five tracers (hydrogen, calcium, magnesium, potassium, and silica) to distinguish “fast” flow paths mainly influenced by the biological subsystem from “slow” flow paths in the geochemical subsystem. The former comprise throughfall, overland flow, and pipe flow and are characterized by a high potassium/silica ratio; the latter are represented by soil water and groundwater, which have a low potassium/silica ratio. Soil water and groundwater differ with respect to calcium and magnesium. The groundwater-controlled streamflow chemistry is strongly modified by contributions from fast flow paths during precipitation events. The high potassium/silica ratio of these flow paths suggests that the storm flow response at La Cuenca is dominated by event water. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 047 KW - Chemistry of fresh water KW - Runoff and streamflow KW - Weathering Y1 - 1995 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-16937 ER - TY - GEN A1 - Howald, Markus A1 - Elsenbeer, Helmut A1 - Laczko, Endre A1 - Schlunegger, Urs Peter T1 - Capillary electrophoresis as a fast and universal tool in soil analysis N2 - Fast analysis of different species of molecules in soils is investigated by capillary electrophoresis (CE). Several CE techniques for the analysis of inorganic ions and carbohydrates have been tested. With regard to the intents of pedologists and the usually large number of soil analyses a bundle of CE systems is proposed, capable of effecting time-saving soil analyses. Adapted electrolyte systems recently published and new separation systems are described. Examples of the application of these methods to two different soil samples are presented. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 070 KW - capillary electrophoresis KW - soil analysis KW - UV-detection KW - inorganic ions KW - monosaccharides Y1 - 1995 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-16913 ER - TY - JOUR A1 - Vorpahl, Peter A1 - Dislich, Claudia A1 - Elsenbeer, Helmut A1 - Märker, Michael A1 - Schröder-Esselbach, Boris T1 - Biotic controls on shallow translational landslides JF - Earth surface processes and landforms : the journal of the British Geomorphological Research Group N2 - In undisturbed tropical montane rainforests massive organic layers accommodate the majority of roots and only a small fraction of roots penetrate the mineral soil. We investigated the contribution of vegetation to slope stability in such environments by modifying a standard model for slope stability to include an organic layer with distinct mechanical properties. The importance of individual model parameters was evaluated using detailed measurements of soil and vegetation properties to reproduce the observed depth of 11 shallow landslides in the Andes of southern Ecuador. By distinguishing mineral soil, organic layer and above-ground biomass, it is shown that in this environment vegetation provides a destabilizing effect mainly due to its contribution to the mass of the organic layer (up to 973 t ha-1 under wet conditions). Sensitivity analysis shows that the destabilizing effect of the mass of soil and vegetation can only be effective on slopes steeper than 37.9 degrees. This situation applies to 36% of the study area. Thus, on the steep slopes of this megadiverse ecosystem, the mass of the growing forest promotes landsliding, which in turn promotes a new cycle of succession. This feedback mechanism is worth consideration in further investigations of the impact of landslides on plant diversity in similar environments. KW - shallow translational landslides KW - tropical montane forest KW - biomass KW - organic layer Y1 - 2013 U6 - https://doi.org/10.1002/esp.3320 SN - 0197-9337 VL - 38 IS - 2 SP - 198 EP - 212 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Zimmermann, Beate A1 - Papritz, Andreas A1 - Elsenbeer, Helmut T1 - Asymmetric response to disturbance and recovery : Changes of soil permeability under forest-pasture-forest transitions N2 - In the humid tropics, continuing high deforestation rates are seen alongside an increasing expansion of secondary forests. In order to understand and model the consequences of these dynamic land-use changes for regional water cycles, the response of soil hydraulic properties to forest disturbance and recovery has to be quantified.At a site in the Brazilian Amazonia, we annually monitored soil infiltrability and saturated hydraulic conductivity (K-s) at 12.5, 20 cm, and 50 cm soil depth after manual forest conversion to pasture (year zero to four after pasture establishment), and during secondary succession after pasture abandonment (year zero to seven after pasture abandonment). We evaluated the hydrological consequences of the detected changes by comparing the soil hydraulic properties with site-specific rainfall intensities and hydrometric observations. Within one year after grazing started, infiltrability and K-s at 12.5 and 20 cm depth decreased by up to one order of magnitude to levels which are typical for 20-year-old pasture. In the three subsequent monitoring years, infiltrability and K-s remained stable. Land use did not impact on subsoil permeability. Whereas infiltrability values are large enough to allow all rainwater to infiltrate even after the conversion, the sudden decline of near-surface K-s is of hydrological relevance as perched water tables and overland flow occur more often on pastures than in forests at our study site. After pasture abandonment and during secondary succession, seven years of recovery did not suffice to significantly increase infiltrability and K-s at 12.5 depth although a slight recovery is obvious. At 20 cm soil depth, we detected a positive linear increase within the seven-year time frame but annual means did not differ significantly. Although more than a doubling of infiltrability and K-s is still required to achieve pre-disturbance levels, which will presumably take more than a decade, the observed slight increases of K-s might already decrease the probability of perched water table generation and overland flow development well before complete recovery. Y1 - 2010 UR - http://www.sciencedirect.com/science/journal/00167061 U6 - https://doi.org/10.1016/j.geoderma.2010.07.013 SN - 0016-7061 ER - TY - JOUR A1 - Schmidt, Lena Katharina A1 - Zimmermann, Alexander A1 - Elsenbeer, Helmut T1 - Ant mounds as a source of sediment in a tropical rainforest? JF - Hydrological processes N2 - In Lutzito catchment on Barro Colorado Island, Panama, extraordinarily high suspended-sediment yields of 1-2Mgha-1year-1 were generated despite the dense forest cover coinciding with erosion-resistant soils. We hypothesized that ant mounding activity is an important zoogeomorphological mechanism in this area, providing relevant quantities of easily transportable material at the soil surface. To test this hypothesis, all ant mound material was collected collected for dry mass determination from thirty 4m2 plots installed in the study area every 1-3days during the 39-day sampling period. Additionally, three ground-nesting ant species responsible for mounds in the study area, Ectatomma ruidum, Trachymyrmex cornetzi and Strumigenys marginiventris, were identified. On the basis of the total of 1.38kg of material collected in the wet season of 2011, the estimate for the whole 8months wet season amounts to 725kgha-1. As this value is in the same order of magnitude as sediment output, it shows that ants may act as important ecosystem engineers and contribute to sediment production here by providing large quantities of fine-grained, readily erodible material at the soil surface for subsequent transport to the streambed. Copyright (c) 2014 John Wiley & Sons, Ltd. KW - ant mounds KW - soil erosion KW - sediment output KW - zoogeomorphology Y1 - 2014 U6 - https://doi.org/10.1002/hyp.10222 SN - 0885-6087 SN - 1099-1085 VL - 28 IS - 13 SP - 4156 EP - 4160 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Zimmermann, Beate A1 - Zehe, Erwin A1 - Hartmann, N. K. A1 - Elsenbeer, Helmut T1 - Analyzing spatial data : an assessment of assumptions, new methods, and uncertainty using soil hydraulic data Y1 - 2008 SN - 0043-1397 ER - TY - JOUR A1 - Barthold, Frauke Katrin A1 - Turner, Benjamin L. A1 - Elsenbeer, Helmut A1 - Zimmermann, Alexander T1 - A hydrochemical approach to quantify the role of return flow in a surface flow-dominated catchment JF - Hydrological processes N2 - Stormflow generation in headwater catchments dominated by subsurface flow has been studied extensively, yet catchments dominated by surface flow have received less attention. We addressed this by testing whether stormflow chemistry is controlled by either (a) the event-water signature of overland flow, or (b) the pre-event water signature of return flow. We used a high-resolution hydrochemical data set of stormflow and end-members of multiple storms in an end-member mixing analysis to determine the number of end-members needed to explain stormflow, characterize and identify potential end-members, calculate their contributions to stormflow, and develop a conceptual model of stormflow. The arrangement and relative positioning of end-members in stormflow mixing space suggest that saturation excess overland flow (26-48%) and return flow from two different subsurface storage pools (17-53%) are both similarly important for stormflow. These results suggest that pipes and fractures are important flow paths to rapidly release stored water and highlight the value of within-event resolution hydrochemical data to assess the full range and dynamics of flow paths. KW - EMMA KW - hydrochemistry KW - overland flow KW - return flow KW - stormflow generation Y1 - 2016 U6 - https://doi.org/10.1002/hyp.11083 SN - 0885-6087 SN - 1099-1085 VL - 31 IS - 5 SP - 1018 EP - 1033 PB - Wiley CY - Hoboken ER - TY - GEN A1 - Elsenbeer, Helmut A1 - Cassel, Keith A1 - Tinner, W. T1 - A daily rainfall erosivity model for Western Amazonia N2 - Rainfall erosivities as defined by the R factor from the universal soil loss equation were determined for all events during a two-year period at the station La Cuenca in western Amazonia. Three methods based on a power relationship between rainfall amount and erosivity were then applied to estimate event and daily rainfall erosivities from the respective rainfall amounts. A test of the resulting regression equations against an independent data set proved all three methods equally adequate in predicting rainfall erosivity from daily rainfall amount. We recommend the Richardson model for testing in the Amazon Basin, and its use with the coefficient from La Cuenca in western Amazonia. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 050 KW - MESOSCALE CONVECTIVE COMPLEXES KW - KINETIC-ENERGY KW - UNITED-STATES KW - EROSION Y1 - 1993 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-16962 ER -